In a surveillance scene with moving objects, such as cars on a highway, it is important to have a correct exposure time. If the exposure time is too long the image and video will become blurry because the objects are moving too fast in relation to the time when light from the scene is collected.
The relation between exposure time and object speed is e.g. known from US2011096202 A1 which discloses overlaying graphical objects, such as snowflakes, autumn leaves or similar, on an image of a scene. The user can adjust the speed of the graphical objects by changing the shutter speed.
A problem which is not addressed in US2011096202 A1 is however how to select an appropriate exposure time. There are many factors that influence the choice of an exposure time, thereby making it difficult to give advice to an operator for how to set the exposure time. There is thus a need for a method which helps an operator in selecting an appropriate exposure time for imaging of moving objects.